Process for the manufacture of dispersoids



Past it... 112, 1923."

warren srAras HERMAN PLAUSON, OF HAMBURG, GERMANY.

PROCESS FOR THE MANUFACTURE OF DISPERSOIDS.

No Drawing.

T o ail whom it may concern V,

Be it known that I, IIERMANN PLAUSON, Esthonian subject, residing in Hamburg, German have invented certain new and useful rocesses for the Manufacture of Dispersoids, ofavhich the following is a specification. I

This invention relates to an improved process for the manufacture of colloidal or dispersoidal suspensions of various substances to various degrees of fineness.

According to the processes hitherto employed, certain solid substances, after being subdivided can be converted into a more or less dispersed condition by;

1. Dissolving in a dispersing medium (reversible colloids).

2. By electrical disintegration in a dispersion medium which is a con-conductor of electricity (irreversible colloids).

3. By the use of chemical means.

These three processes of treatment may also be divided into two main classes firstly, the condensation methods employing chemical means, and dispersion methods in which the particles are scattered (Zerstaubung).

As is well known the .dispersion method is based on the discovery of Bredig, that if an electric are be formed between two electric points or'wires under water, the metal' age spark be caused to jump in a dispersion medium between two points of the metal to be dispersed.

The dispersion method by means of an electric arc can only be carried out with substances which are conductors of electric current, such as metals, and this method cannot be used for the dispersion of non-conductin substances or even chemical compounds suc as oxides,-hasic salts, dyes of all kinds and the like. Yet it is of very great technical,

value to be able todisperse these substances as finely aspossible and without chemical means; thus. in thecase of dyes or paints the covering power,,col0ur effect and other properties may be much improved. By the useof the process: of the present invention cheap common kinds'of colours may be. im-

Ap ilication filed January 13, 1921. Serial No. 437,117.

proved in properties in a very simple way.

a My invention relates to a generalprocess for the dispersion of substances.

I The new process is based on the fact observed by me that when varioussubstances (e. g. ores, dyes, sulphur, cellulose, etc.) in a previously ground condition are continuously pounded or rubbed with a quantity of a suitable liquid dispersion medium, which isa non-conductor of electricity or only sli htly conducting, with sufficient force'and for'sufiicient length of time in an impact mill or discpin, or the like mill (e. g. a dismembrator or Kreuz mill) it is possible to convert many such substances into a more or less finely dispersed or colloidal condition. By the addition of small quantities'of protective colloids during the grinding, the dispersion effect can not only be considerably increased but the substances can also be kept for a long time and used with'their dispersion media as colloids solutions. The process may be carried out with the above mentioned mills if the liquid escaping therefrom, be constantly returned thereto by means of a pump.

In the application of the process of the present invention to mills of usual type it' has been found that often considerable practical difliculties are present. With some substances, such for example as cellulose, the fine sieves of the usual form of grinding mill would become clogged or stopped and the machines consequently immediately lose its efiect.

Apparatus consisting of a beating mill, a pump and the necessary intermediary pipes are therefore inmost cases ill adapted for making homogeneous dispersoids by the process of the invention above indicated, it being only possible to convert them unevenly and with considerable loss of efficiency and ultimately the fine dispersed parts have to be separated from the coarser. It is however to be understood that in case of need, a result can be obtained even with such ap pri-ratus of usual type.

The full benefits of the invention are obtainable with a novel type of rapid running heating or friction mill that is to sayin a mill in which the peripheral grind ing speed is at least 1000 metres per second, whilst it has been found that for the purpose of the manufacture of colloidal suspensions, the efiiciency rapidly increases with increases in peripheral speed above this value. The most important advantage of these machines is that with them almost mono-dispersed or socalled isosegmatic systems can be obtained and coarse substances of the most varied kinds can be converted into a dispersed condition.

Reference may be had to British Patents 179002 and 179003 for illustrations of disersion machines suitable for use in carryin out the processes described herein.

y employing one of the dislpersion machines hereinbefore mentione the most varied substances may be converted into the very finest dispersed condition if only suitable dispersion media, temperatures, and proportionate quantities are employed. In order to be converted into a suliiciently finely dispersed condition many substances require varying lengths of time of treatment.

Small additions of media which serve for assisting the dispersion or act as protective colloids for dispersions greatly facilitate and accelerate the process.

The process will be better explained by the. following examples.

parts of distilled water and 10 parts of flowers of sulphur are beaten for from 3 to 5 hours in a dispersion machine of the percussion type, at ordinary room temperature. During this time the entire sul: phur is converted into a finely dispersed condition and behaves like colloidal sulphur solution made by chemical means. if the solution be allowed to stand for from 1 to 2 hours after beating small quantities of the sulphur suspension are precipitated, whilst part of the remainder remains a long time in a colloidal condition. If during the heat ing 1 to 3% of protective colloidssuch as protein, gelatinc, glycerine'. neutral soaps and like substances be added thereto a sol phur dispersion in water of great fineness is obtained. By the addition during the beating of small quantities of substances which dissolve sulphur for instance benzol, benzene. carbon-bi-sulphide, or the like, the beating time may be shortened by half and 30 to 40% of the sulphur oven converted during this time into the condition of amierons (particles of exceptional fineness).

Molten sulphur may also in a similar manner be converted into a dispersed or colloidal condition. By heating the dispersion medium to 90-90 C. the dispersion process is further accelerated. but then the beating must be continued with simlutane ous cooling until the temperature of the liquid has descended to 25-30" otherwise the sulphur is precipitated or becomes fiocculent.

The process may however also be regard ed as a refining process of the sulphur after being converted into a dispersed condition massesis precipitated by the addition of small quantities of acid, washed and then afresh converted into a despersed condition in pure water in accordance with this invention.

As by this invention sulphur can be converted into a very finely dispersed condi-,

tion without the 'use of chemical means, which was not possible hitherto by other generally known methods, a sulphur solution is obtained of extraordinary value for various purposes. The dispersion medium may also be more or less removed by careful evaporation in vacuo and thereby coucentrated solutions may also be formed. Instead of water an organic dispersion medium may also be employed.

If less sulphur in proportion to the water be employed the degree of dispersion is still It is not advisible to proceed beyond the ratio of 1 to 9 as then the dispersion is slower and not so complete without the use of accelerating catalysts and the addition of protective colloids. Such colloidal solutions are applicable for the disinfection of trees, vines and the like, also for surgical and the like purposes.

[Trample $3.

15 parts of crude graphite previously washed with boiling water and 100 parts of water are trituratcd at a temperature of from 80-90 C. for 5-l0hours (preferably by the use of a grinding machine and this is continued under strong cooling until the temperature of the liquid has sunk to 25 C. The mixture obtained is then pumped into a hollow cylinder and allowed to stand for 1} to 2 hours. After this time the-dispersion medium with the floating graphite particles is carefully separated. bv decanting. from the bottom layer. freed by treatment in a centrifugal from excess water and dried. About 60435)? of colloidal graphite is thereby obtained which forms an excellent lubricant for machinery.

The sand and other particles of impurity are deposited on the bottom and can be utilized for making crucibles and the like coarse articles. By the addition of 1-37}. potash-olein soap. also tannin and phenol sulphonic-acids such as uaphtlio-disulphonic acids the process may be accelcraliul whilst by a preliminary trcutmcnt with alkali. washing, and a fresh dispersion the yield may be increased to about ill-Ti If. Other dispersion media may be taken in place of water for example, graphite previously fr'ccd from ushy constituents by chemical menus may be converted into a finely dispersed condition in oils or in petroleum and the lilcc. in similar manner an extremely fine dispcrsion of talc of the best imaginable quality has been obtained and also lan p black of high quality may be. obtained irom cheap qualities of soot even from wood and the like.

Ew'ample 1 part ofolein soap and 10 parts of coarse grained ultramarine (as a product of wet inding) are, after previous washing with ot water (in order to remove traces of sodium compounds) beaten for ground with 100 parts of cold water for 1-3 hours, During this time the material becomes very finely dispersedand remains floating in the water. It is now allowed to stand and the dispersed material separated by .decantation from any coarse material. Excess water may be removed in a centrifugal, and on careful drying 86-95% fine colloidal colouring material of extremely high covering power can be obtained without the time consuming and expensive sludging such as has hitherto been done in the previously known processes, bein necessary.

nstead of Water, organic dispersion media, such as benzol, alcohol alone or with the addition of small quantities of oil and (or) alternatively ployed, if a partlcularly good kind of turpentine or oil colour is desired,

In similar manner low value kinds of earth and metallic colours (such as iron, cobalt, nickel, zinc, chrome colours) or lithopone, as well as other substances employed for dye purposes may be converted into a finely dispersed condition. Instead of soap small quantitiesof alkali or 'oils or phenolsulghonic acids e. g.naphthol-di-sulphonic aci may be added as accelerators. In some cases tannin or other deflocculating agents may be used. In colours which are to be mixed with oil, in special cases instead of Water'an organic dispersion medium may be used with or without small uantities oi oil or lacquer solvent. The resu t of this is that the colours obtained in this way mix well with the oil added in large quantities before use and have extremely good separating and spreading power.

The colloid mill afi'o ds still greater advantages if at the moment of forming colouring substances or dyestufis, the initial substances are not treated by the ordinary method but in the colloid mill, in such a way lithopone, lead-colours and the like can be obtained in extremely fine dispersion with ra idity such as is impossible in other ways.

f an enamel substance, artificial 0r natural resin, size, cellulose ester, copal or the like is taken and to these small quantities of a solvent ,'(510% as dispersion accelerator) are added-and this mixture dispersed in suitable organic solvents, by the machine novel enamels are obtained in which the lakes are not dissolved but dispersed.

with or without the addition 1-3% gelatine, protein (albumen) or soap without or still are beaten u turpentine may be em-.

of 15% free alkali, in the machine at a temperature ofs90 for 3-5 hours. In this time there is formed an opalescent liquid in which the presence of cellulose is not manifest. If the mixture is further beaten until the temperature has sunk to 20 C., after 10 minutes standing the cell structure of the cellulose can no longer be seen with a hundredfold enlargement through the microscope' The finely distributed cellulose thus obtained may be rendered fiocculent by means of acid and (or) acid salts. By evaporating under vacuum a substance is finally obtained which can no longer be described as cellular in structure but rather resembles celluloid. This is homogeneous and may be formed under pressure into articles of various kinds even without the addition of adhesives if better with the addition the moulds are heated at a temperature of 120150 C. under 100 to 300 atmospheres pressure. Similar product can be obtained by the new machines from wood pulp or the like with a suificient uantity of water, temperature and colloiddi accelerating and also protective means. Further, organosols of cellular materials such ascellulose may be obtained b means of benzol, acetone and the like, while small quantities of cellulose ester soluble in acetone have been found to be good accelerators of dispersion. In addition to treating the ordinary pulp used. in paper-making which has been opened out 1n known manner, it is also possible to use untreated wood constituents, such for instance as sawdust, to convert them into a very fine dispersed condition and obtain a homogeneous product therefrom which has quite different properties and appearance to wood.

A special advantage of such dispersed cellulose is that it can be converted much easier and more completely into cellulose ester and products available for artificial silk and the like can advantageously be obtained.

5. Further while by ordinary wet grinding the technical disintegration can be carried up sandth), by my process it can be carried easily up to 0.0001 m. m. (one-hundred thousandth.)

6. Substances made by this dispersion process show colloidal properties, but those made in accordance with grinding methodsdo not.

The theoretical basis which in this process in many cases governs the almost molecular dispersion consist according to my observations, inst at in the treatment of solid substances in' a sufiicient current of non-conducting fluid dispersion medium by rapid strong beating or friction on the separate particles of the substance, a momentary pressure action of hundreds of kilograms may be obtained which is to be regarded as to the limit 0.001 m. m. (one-thou the ordinary wet I the main cause of the dispersion. It is to be assumed that in such colossal, momentarilyv l vzer of the line dispersions. That the static electrical power here formed by beating mainly effects the dispersion also appears from the factthat no colloidal condition can be obtained by grinding even in beating mills with dispersion media in the presence of good electrolytes (without protective colloids); only when sullicient protective colloids are added to the dispersion media is the appearance again evident and then only with weak electrolytes. However the pro cess has been described so that it can be performed without the aid of this theory.

It may be useful to summarize the conditions of success for rapid operation on a commercial scale since it is considered that the present application contains the first disclosure of such conditions leading to a commercially applicable general method for obtaining dispersoids mechanicallv. Broadly speaking it is necessary to use an extraordinary and .hitherto unprecedented intensity of comminution and it is found that increasing this intensity shortens the time of operation in quite a disproportionate manner so thateconomically it is necessary to operate at very high speeds. When disintegrating mechanically in a non-electrolyte without the aid of the hereafter described artifice, it is necessary to employ a peripheral speed of about 6,000 metres per minute, e. g. in av disintegrater having beater arms. This is the first condition.

Secondly, it has been found that in all cases it is necessary to employ a non-electrolyte or at any rate a very weak electrolyte unless certain artilices are employed. In the same way the material to be dispersed must not form an electrolyte with the dispersion medium.

Thirdly, it is of the reatest importance to use a large amount of the liquid dispersion medium. In practice. at least 90% of liquid or more is employed to 10% of solid and in any case there must be at least T0); of liquid to obtain commercial results. i

The above peripheral velocity is very high and the following further means can be employed to reduce it, but whether these means are employed or not the minimum velocity should be in the neighbourhood of about 2,000 metres per minute. The economic advantage of using a. high speed increases sharply about this point if efficiency is expressed as a function of speed.

Fourthly then the velocity can be'reduced to 2,000 metres per minute if very high pressures are employed in cases when grinding mills are used. g

F iftl ly, the necessary speed can be re-.

duced by using dispersion accelerators which may be classified as follows: I 1 I (a) Chemical agents which are known to be solvents of the material to be dispersed to a greater or less extent, e. g. acetone or sulphur.

I cal compounds of a labile nature with the dispersion medium in question which-have colloidal properties provided that free ions are not formed in the dispersion medium or only very slightly. With an excess of the dispersion medium these labile compounds are decomposed and reformed. Example, addition of alkali in the dispersion of protein, wood, etc.

,(0) Chemical agents which have the power of assisting the formation of complex compounds between the material to be dispersed and the dispersion medium. One type of such compounds is given by tannin which powers assist graphite particles to become hydrated by water molecules. Another type is illustrated is the addition ofsmall quantities of sulphuric acid or phosphoric acid and the manufacture of colloidal phosphates- At this point I may refer to my prior British patents of 1913, e. g. #17729/13 which. describes the mechanical disintegration of carbonaceous materials and contrasts this process with the work of Acheson on using tannin as a defiocculating agent. My British patents mention that the material is ground, for instance with oil or water at high speed or heavy pressure. It will be seen from the above description that" this patent does not disclose the necessity of employing speeds of about 2,000 metres per minute to o tain rapid results, nor does it set forth general principles which would enable aspecific process for treating car- Chemical agents which form chemi bon or carbonaceous substances to be gen-- and it was not possible to foresee general conditions in which other substances could be mechanically converted into the colloidal state. I

The apparatus which has been described is of particular value for commercially performing the invention. In the disintegrator type of colloid mill, important features are the eccentric mounting of the heaters so that an automatic circulation is obtained and the concentration of the action on a. limited number of points or on one point by using a limited number of heaters. If the usual number of beaters is employed, it wouldbe impossible to drive a mill on a commercial scale owing to the enormous li uid resistance, In the frictional type of ediloid mill, important features are the extorloidal dispersions which consists in subjecting the substance to be dispersed and a liq- \lltl dispersion medium to intensive mechanical disintegration under the following conditions. v17, (/1) cmployluc a peripheral speed of not less than 2,000 metres per minute. (1)) using a liquid which is not a good electrolyte. and (c) using a mixture in which the total quantity of liquid comprises at least T0)? of the mixture.

2. A process as claimed in claim 1 in which about 90% of dispersion medium is used.

3. A process as claimed in claim 1 in which a dispersion accelerator is added.

4. A process as claimed in claim 1 in which a protective colloid is added.

5. The process of obtaining valuable industrial colloidal products from raw materials of different chemical constitution which includes the step of effecting a chemical reaction during dispersion in a colloid mill at a peripheral speed of not less than 2000 meters per minute and-in presence of an excess of liquid dispersion medium suflicient to amount to at least 70%"0f the mixture.

(i. A process for the preparation of colloidal sulphur as claimed in claim 1.

7. A process for rapidly dispersing materials by subjecting them to intensive mechanical disintegration at very high speed in presence of at least 90 parts dispersion medium to 10 parts of materials to be dispersed.

In witness whereof. I have hereunto signed my name this '30 day of Dec. 1920,

in the presence of two subscribin witnesses.

v HERMANN PL USON. \Vitnesses:

HECTOR ARMSTRONG, W. H. Bmas'mN. 

